Rectangular convergence guide



Nov. 21, 1967 M. s. HERRING 3,353,210

RECTANGULAR CONVERGENCE GUIDE Filed Dec. 9, 1965 INVENTOR MILTON S. HERRING BY MZMW ATTORNEY United States Patent )fifice 3,353,210 RECTANGULAR CONVERGENCE GUIDE Milton S. Herring, Kinston, N.C., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del, a corporation of Delaware Filed Dec. 9, 1965, Ser. No. 512,713 2 Claims. (Cl. 188) ABSTRACT OF THE DISCLOSURE An improvement in an apparatus for melt spinning a large number of filaments at high speed from a single spinneret in which the filaments are converged into a bundle and finish is applied before the filaments pass to a take-off wheel, the improvement being a convergence guide for assembling the filaments into a yarn bundle of uniform, essentially rectilinear cross sections, the guide having an essentially linear primary yarn-contacting surface of smoothly rounded contour for converging the filaments into a flat bundle and contiguous yarn-contacting surfaces of smoothly rounded contour for controlling the yarn bundle width, the surfaces being joined in smoothly rounded contours, and the yarn-contacting surfaces of the guide form an essentially rectilinear aperture having rounded ends.

This invention is concerned with guides for synthetic filamentary materials and more particularly with an improved guide for unfinished, freshly melt-spun yarns which are especially susceptible to mechanical damage or twining.

In the production of melt-spun fibers, such as commercial polyarnide and polyester yarns, it is common practice to shape a multiplicity of filaments by continuous extrusion of the molten polymer through a single spinneret. Prior to application of a finish, which serves to protect the filaments against mechanical damage, the large number of filaments must be converged to a bundle having a relatively small cross-sectional area for convenience in subsequent handling. The convergence guide previously used for this purpose has a circular aperture and is mounted somewhat off-center of the straight line extending from the center of the spinneret to the first point of yarn contact downstream from the convergence guide. This results in crowding of all the filaments against a fraction of the circular guides circumference and forces the bundle into a roughly oval shape. It has been found that the shape of the filament bundle obtained with a guide of this type is not optimum for at least two reasons: 1) The oval shape results in a fundamentally unstable filament orientation in that the filaments tend to wander from position-to-position within the limits of the bundle cross-section. This results in an undesirable degree of filament-to-filament contact between the guide and the spinneret, and leads to mechanical damage and adherence of two or more still-molten filaments to form a single filament of larger denier; these effects are exaggerated with high speed operation. (2) The oval shape is reflected in a non-uniform spread of filaments downstream from the convergence guide on the rotating roll employed to apply the protective finish. Some filaments near the edge of the bundle are excessively exposed'to the film of finish on the roll, while others near the center of the bundle receive no finish at all. It has been found that, even when the filaments are apparently closely packed in a bundle, they intimately contact each other only infrequently and that a thin layer of protective finish on a given filament will migrate to an adjacent, unfinished filament very slowly, if at all. This is especially true of a finish which, after evaporation of the water in which it is dispersed, has a high viscosity.

This invention provides an improved means for the convergence of hot, freshly melt-spun filaments of synthetic linear condensation polymer. It further provides means for converging freshly melt-spun filaments which is capable of maintaining rectilinear distribution of filaments in the bundle cross-section. It also provides a means for obtaining an improvement in uniformity of finish application among filaments in a bundle. Other advantages will be seen as the description of the invention proceeds.

These advantages are provided, in apparatus for melt spinning a large number of filaments at high speed from a single spinneret wherein the hot filaments are converged into a bundle and a protective finish is applied before the filaments pass to a take-off wheel, by the improvement of a convergence guide for assembling the filaments into a yarn bundle of uniform, essentially rectilinear crosssection. The guide has an essentially linear primary yarncontacting surface of smoothly-rounded contour for converging the filaments into a flat bundle and contiguous yarn-contacting surfaces of smoothly-rounded contour for controlling the width of the fiat bundle. The surfaces are joined in smoothly-rounded contours to minimize filament damage. Preferred guides have the surfaces arranged to form essentially rectilinear or square apertures.

A preferred embodiment of this invention comprises a guide with an essentially rectilinear aperture having rounded ends. Such a guide can be rotated 180 to present a second surface to the yarn when said first surface has become so eroded by contact with the running yarn as to be unacceptable. Another guide embodiment has an essentially square aperture with rounded corners; it can be reset at index angles to present, successively, each of four yarn-contacting guide surfaces. While obvious economy is found in such embodiments, successful operation of this invention depends only on a guide with a closed aperture which has at least one essentially linear rounded surface of suitable length to provide a uniform, essentially rectilinear cross-section in the bundle of filaments passed thereover.

This invention is more readily understood by reference to the following description taken with the drawings.

FIGURE 1 is an over-all schematic diagram of the spinning apparatus showing location of the convergence guide of this invention,

FIGURE 2 is a plan view of a preferred embodiment of the guide of this invention,

FIGURE 3 is a sectional elevational taken on line 33 of FIGURE 2, and

FIGURE 4 is a plan view of an additional embodiment of convergence guide.

With reference to FIGURE 1, molten polymer from source (not shown) is melt spun through a conventional spinneret 1 and shaped thereby into multiple filaments 2. Convergence guide 3, mounted in fixed support 4, is set forward of the threadline such that the filaments slide across the back surface of its aperture as indicated by the layer of filaments 2 in FIGURE 2. Convergence of the filaments within the substantially vertical plane which includes the back surface of the convergence guide continues beyond the guide as required by contact of the bundle with a driven take-0E wheel 5, which rotates at a fixed speed around a shaft oriented perpendicular to said vertical plane. The filaments may make a full wrap around the take-0E wheel, as shown, or several wraps around a take-off wheel and a separator roll, or may only wrap part way around the wheel. Between convergence guide 3 and feed wheel 5 is positioned finish Patented Nov. 21, 1967.

an alternative, is frequently of greater interest because of the economy representedby elimination of the preliminary packaging of individual bundles on bobbins.

FIGURES 2 and 3 are, respectively, plan and crosssectional elevation views of a preferred embodiment of the. convergence guide of' this invention. In FIGURE 2 aschematic representation of the approximate distribution of filaments inthe bundle cross-section during yarn production is shown. This embodiment has two equivalentrounded guide surfaces and 11. Inthe alternative embodimentshown in FIGURE.4 there are four equivalent guiding surfaces 12, 13, 14and 15. A sectional elevation of'thisembodiment would correspond to FIG- URE 3. With either embodiment, scheduled indexing of the guide to present an unworn surface to the yarn provides: a desirable economy.

The-advantages of. this invention are seen in improved yarn quality, particularly with respect to a reduction in number oftwinned filaments and in improved uniformity of finish application. An immediate observable improvement in yarn quality is presumed to bedue to fewer'and less-severe filamentinteractions in the hot zone between; the spinneret and theconvergence guide, where the filaments are particularly prone to merge into larger fil-amentsor to be. damaged by contact with each other. More uniform filament-.to-filament finish application provides, superior protection for the filaments in subsequent processing. steps, as in' intermediate packaging on individual-bundle bobbins or in handling as a tow representing::a-plurality of'individual bundles, and in guiding tOfthG drawingstep whereinthe filaments are drawn to several times-the as-spun length. Generally the spin finish isextracted fromthe fiber in hot-wet drawing, and is subsequently replaced by-a .final finish .before drying and relaxing, crimping, cutting and packaging. It has been found, however, that uniform finish application in the asspunxyarn is important to uniform distribution of filaments in the tow bundle vfed to the draw zone and minimizesmechanical damage tofilaments during the guidingemployedyto accomplish this uniform distribution.

In a direct comparison between use of the circular convergence guide of the art and the rectangular guide of this invention in high-speed'meltspinning of polyethylene terepht-halate,pthe advantages in uniformity of finish application are clearly apparent, as summarized in the following. table:

In another test, the yarn was examined for fused filaments which result from filament-to-filament contact nea the sra h e he filam s a e s i me ee t one condition of air-flow rate, instances were reduced 95% by substitution of'therectangular guide forthe circular guide of the art. At at high air-flow rate in this sensitive zone of filament travel between the spinneret and the guide, a reduction in frequency of was accomplished by substitution of the rectangular guide for the circular convergence guide of the art.

lthough additional embodiments beyond those specifically described will meet the critical requirements of this invention, i.e., that the guide present an essentiallylinear rounded surface for yarn contact of suitable length to result in a uniform distribution of filaments along said linear surface and that'the said surface be contiguous with other surfaces which combine to enclosethe running yarn, the combination of straight pins as a substitute for such structure has notbeen found satisfactory due to entanglement of filaments on such a combination guide with an occasional break-back of a bundle of filaments. Since many different embodiments of theinvention may be made without departingfrom'the-spirit and scope" thereof, it is to be understood that the invention is not limited by the'specific illustrations except to the extent defined in the following'claims:

I claim: 1. In apparatus for melt spinning a'large number of filaments at high'speed from a'- single spinneret'wh'erein the hot filaments are'converged into a'bundle and a protective finish is applied before the" filaments pass to a take-off wheel, the improvement of a convergence" guide for assembling the filaments'into a yarn bundle'ofuni form, essentially rectilinear cross-section, said guide having an essentially linear primary yarn-contactingsurface of smoothly-rounded contour for 'converging' the fila: ments into a fiat bundle and contiguous"yarn-contacting surfaces of smoothly-rounded contour for controlling the" width of the yarn bundle, wherein said yarn-contacting surfaces of the convergence guide form an essentially rectilinear aperturehaving rounded ends, said surfaces being joined in smoothly-rounded contours;

2; An apparatus for melt spinning a-large number "of filaments at high speed from a single spinneretwherein the hot filaments are converged-into a bundle and a'protective finish isapplied before the filamentspass to' a take-off wheel, the improvement of'a convergence guide for assembling the filaments into a yarn bundle of uniform, essentially rectilinear cross=section, said guide haw ing an essentially linear primary yam-contacting surfaceof smoothly-rounded contour for converging'the filaments into a flat bundle and contiguous yarn-contacting sur faces .of smoothly-rounded contour'for controlling the width of the yarn bundle, whereinsaid yarn-contactingsurfaces of the convergence guide'form an essentially square aperture with rounded corners; said surfaces be= ing joined in smoothly-rounded contours;

References Cited UNITED STATES PATENTS 2,273,105. 2/ 1942 Heckert. 2,539,980 1/ 1957 Van Hall. 2,860,373 11/1958 Schmidt 18-8 3,041,662 7/1962 Cochran l8*8' X FOREIGN PATENTS 601,485 V 7/ 1960' Canada. 325,714 2/ 1930. Great Britain.

I; STEPHENSON, Primary Examiner. 

1. IN APPARATUS FOR MELT SPINNING A LARGE NUMBER OF FILAMENTS AT HIGH SPEED FROM A SINGLE SPINNERET WHEREIN THE HOT FILAMENTS ARE CONVERGED INTO A BUNDLE AND A PROTECTIVE FINISH IS APPLIED BEFORE THE FILAMENTS PASS TO A TAKE-OFF WHEEL, THE IMPROVEMENT OF A CONVERGENCE GUIDE FOR ASSEMBLING THE FILAMENTS INTO A YARN BUNDLE OF UNIFORM, ESSENTIALLY RECTILINEAR CROSS-SECTION, SAID GUIDE HAVING AN ESSENTIALLY LINEAR PRIMARY YARN-CONTACTING SURFACE OF SMOOTHLY-ROUNDED CONTOUR FOR CONVERGING THE FILAMENTS INTO A FLAT BUNDLE AND CONTIGUOUS YARN-CONTACTING SURFACES OF SMOOTHLY-ROUNDED CONTOUR FOR CONTROLLING THE WIDTH OF THE YARN BUNDLE, WHEREIN SAID YARN-CONTACTING SURFACES OF THE CONVERGENCE GUIDE FORM AN ESSENTIALLY RECTILINEAR APERTURE HAVING ROUNDED ENDS, SAID SURFACES BEING JOINED IN SMOOTHLY-ROUNDED CONTOURS. 